This invention relates to sewing machines, and more particularly, to a blindstitch sewing machine, that is, a machine for producing stitches the threads of which enter and emerge from the back side of the work without surfacing and thus being invisible from the front or exposed side of the work.
Blindstitch sewing machines presently known in the art are expensive, special purpose, industrial machines intended for use primarily by trained operators, tailors, or the like. Not only does the cost deter use of known blindstitch sewing machines by occasional or untrained operators familar only with household sewing machines, but also the rather striking differences in arrangement and operation of the blindstitching instrumentalities as compared with those of household sewing machines, as well as differences in the mode of threading of the stitch forming instrumentalities and differences in the disposition of work fabrics as they are directed to the point of stitch formation.
The present invention not only provides a novel organization of parts in a blindstitch hemming machine which makes possible great economy in the manufacture of parts and in the assembly thereof so as to reduce the cost of a blindstitch machine to a level well within a range affordably by an occasional non-professional user; but also facilitates threading, work handling, and the aspect of an operator of the blindstitch machine with respect to the stitch forming instrumentalities so as to minimize the differences from conventional household sewing machines and thus facilitate the use thereof by an occasional sewer.
This invention contemplates a blindstitch sewing machine having a two part frame including a base portion with a substantially planar walled floor from which a plurality of bosses rise for supporting the blindstitching mechanism which comprises essentially, a thread carrying endwise reciprocatory needle, a thread manipulating looper, and a work feeding mechanism as well as a main drive shaft with actuators for the blindstitching mechanism and an electric motor with drive connections to the main shaft. This base portion construction provides not only for high dimensional stability for the blindstitching mechanism but for facility of assembly thereof into the base portion prior to placement thereon of a cover portion including a low section extending from one side to the other across the entire front of the cover portion, a high rear section, a sloping ramp section joining the front and rear sections and walls depending from at least the sides and rear of the cover portion mating congruently with the walls of the base portion. A throat plate is carried at one side of the frame adjacent the low section of the cover portion, and across the front of the machine frame an access opening is formed between the base and cover portions adapted to be closed or opened selectively by a shiftable cover and adapted to accommodate on that side opposite the throat plate, a thread spool holder, thread controlling instrumentalities and thread guides, and adapted to accommodate the thread carrying needle of the blindstitching mechanism beneath the throat plate, so that threading may be accomplished directly across the front of the machine in full and direct view of the machine operator. A presser arm pivotally secured at the opposite side of the frame from the throat plate on the high rear section of the frame cover portion, projects forwardly from the high rear section of the cover portion, has a thickness dimension substantially equal to the difference in height of said low and high cover portion sections and carries a presser device for urging work fabric against the throat plate as well as a ridge former for projecting a bight of work fabric through the throat plate aperture. With this construction, the blindstitch forming mechanism which is strange to most users of household sewing machines and apt to detract from their attention during operation, is hidden from view by the presser arm and the low silhouette of the presser arm does not detract the operator's view of the flow of work through the blindstitch sewing machine.